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SuSE alert: samba

Sebastian Krahmer, SuSE Security Team, reviewed security-critical parts of the Samba server within the scope of security audits that the SuSE Security Team conducts on a regular basis for security-critical Open Source Software. Buffer overflows and a chown race condition have been discovered and fixed during the security audit. The buffer overflow vulnerabilitiy allows a remote attacker to execute arbitrary commands as root on the system running samba. In addition to the flaws fixed in the samba server, some overflow conditions in the samba-client package have been fixed with the available update packages. It is strongly recommended to install the update packages on a system where the samba package is used.

Resent for Announcement-ID change from SuSE-SA:2003:015 to SuSE-SA:2003:016

Sebastian Krahmer, SuSE Security Team, reviewed security-critical
parts of the Samba server within the scope of security audits that
the SuSE Security Team conducts on a regular basis for security-critical
Open Source Software.
Buffer overflows and a chown race condition have been discovered and
fixed during the security audit. The buffer overflow vulnerabilitiy
allows a remote attacker to execute arbitrary commands as root on the
system running samba. In addition to the flaws fixed in the samba
server, some overflow conditions in the samba-client package have
been fixed with the available update packages. It is strongly
recommended to install the update packages on a system where the
samba package is used.

There exists no temporary workaround against this vulnerability other
than shutting down the smbd daemon.

We would like to thank the Samba Team, especially Jeremy Allison, Andrew
Bartlett and Volker Lendecke for their quick response and cooperation.

To find out which packages are installed on your system, you may run
the following command:

rpm -qa|egrep '(samba|smbclnt)'

Please download the update package for your distribution and verify its
integrity by the methods listed in section 3) of this announcement.
Then, install the package using the command "rpm -Fhv file.rpm" to apply
the update.
Our maintenance customers are being notified individually. The packages
are being offered to install from the maintenance web.

SPECIAL INSTALL INSTRUCTIONS:
==============================
After successfully installing the update packages, you should restart
the samba server process(es) to make the changes in the system effective.
If you do not have a samba server running on your system, no further
action is required. If you have a samba server running, please run the
following command as root:

- wget
New wget packages are available which filter certain characters
such as .. and / in filenames to ensure evil servers cannot overwrite
important system-files or files outside the current directory.

SuSE update packages are available on many mirror ftp servers all over
the world. While this service is being considered valuable and important
to the free and open source software community, many users wish to be
sure about the origin of the package and its content before installing
the package. There are two verification methods that can be used
independently from each other to prove the authenticity of a downloaded
file or rpm package:
1) md5sums as provided in the (cryptographically signed) announcement.
2) using the internal gpg signatures of the rpm package.

1) execute the command
md5sum <name-of-the-file.rpm>
after you downloaded the file from a SuSE ftp server or its mirrors.
Then, compare the resulting md5sum with the one that is listed in the
announcement. Since the announcement containing the checksums is
cryptographically signed (usually using the key security@suse.de),
the checksums show proof of the authenticity of the package.
We disrecommend to subscribe to security lists which cause the
email message containing the announcement to be modified so that
the signature does not match after transport through the mailing
list software.
Downsides: You must be able to verify the authenticity of the
announcement in the first place. If RPM packages are being rebuilt
and a new version of a package is published on the ftp server, all
md5 sums for the files are useless.

2) rpm package signatures provide an easy way to verify the authenticity
of an rpm package. Use the command
rpm -v --checksig <file.rpm>
to verify the signature of the package, where <file.rpm> is the
filename of the rpm package that you have downloaded. Of course,
package authenticity verification can only target an un-installed rpm
package file.
Prerequisites:
a) gpg is installed
b) The package is signed using a certain key. The public part of this
key must be installed by the gpg program in the directory
~/.gnupg/ under the user's home directory who performs the
signature verification (usually root). You can import the key
that is used by SuSE in rpm packages for SuSE Linux by saving
this announcement to a file ("announcement.txt") and
running the command (do "su -" to be root):
gpg --batch; gpg < announcement.txt | gpg --import
SuSE Linux distributions version 7.1 and thereafter install the
key "build@suse.de" upon installation or upgrade, provided that
the package gpg is installed. The file containing the public key
is placed at the top-level directory of the first CD (pubring.gpg)
and at ftp://ftp.suse.com/pub/suse/pubring.gpg-build.suse.de .

- SuSE runs two security mailing lists to which any interested party may
subscribe:

suse-security@suse.com
- general/linux/SuSE security discussion.
All SuSE security announcements are sent to this list.
To subscribe, send an email to
<suse-security-subscribe@suse.com>.

suse-security-announce@suse.com
- SuSE's announce-only mailing list.
Only SuSE's security announcements are sent to this list.
To subscribe, send an email to
<suse-security-announce-subscribe@suse.com>.

For general information or the frequently asked questions (faq)
send mail to:
<suse-security-info@suse.com> or
<suse-security-faq@suse.com> respectively.

The information in this advisory may be distributed or reproduced,
provided that the advisory is not modified in any way. In particular,
it is desired that the clear-text signature shows proof of the
authenticity of the text.
SuSE Linux AG makes no warranties of any kind whatsoever with respect
to the information contained in this security advisory.